Intro. to Histology Flashcards
Light Microscopy
used to visualize and study the cell from a structural standpoint
Phase Contrast
type of light microscope that allows you to see structures without staining
Polarizing
- requires a stain for visualization and fixation
- has a filter that adds a third dimension
Confocal
- increases optical resolution and contrast of a micrograph by using point illumination and a spatial pinhole to eliminate out-of-focus light in specimens that are thicker than the focal plane. It enables the reconstruction of three-dimensional structures from the obtained images.
- Requires some staining/dye
Electron Microscopy
- physics principle is similar to how x-rays work
- The penetration rate and strength to penetrate the skin/structure causes scattering when bouncing off objects, creating an image of the structures not penetrated.
(TEM and SEM)
Principle of Birefringence
optical property of a material having a refractive index that depends on the polarization and propagation direction of light
TEM (Transmission Electron Microscope)
allows you to see inside the cell through the plasma membrane
SEM (Scanning Electron Microscope)
- allows you to see the electrons being repelled off of the surface
- never in color
Color stains and type of cell.
Blue/Black: Basophilic
Pink/Light Pink: Acidophilic
Red/Orange: Eosinophilic
Grey/Light Grey: Neutrophilic
To be considered an organ, there must be at least __ types of tissue present.
2
The largest most complex organ of the body, containing all 4 types of tissue.
skin
Messenger in and out of the nucleus.
mRNA
Two types of chromatin.
Heterochromatin: chromatin is coiled tightly and dark
Euchromatin: uncoiled DNA and lighter in color
Functions of the epithelium.
Cell Structure & Filtering - Organized by Nature, Like to Stack in layers Cell Polarity & differentiation Cell metabolism Cell signal transduction Intercellular interaction (i.e. NMJ)
Basal Lamina vs. Basement Membrane
- Basement membrane is term in light microscopy
- Basal Lamina is term in Electron Microscopy because more detail is visible and discernible
CAMs
cell adhesion molecules
Immature connective tissue.
mesenchyme, mucous
Loose connective tissue (mature).
Areolar, Adipose, Reticular
Dense connective tissue (mature).
Regular, Irregular, Elastic
Cartilage (mature).
Hyaline, Fibrous, Elastic
Specialized mature connective tissue.
Bone
Blood - specialized function is oxygenation
Lymph - specialized function is immunity
Two types of nervous tissue.
neurons, glial cells
Largest protein structure you can see.
proteoglycan
Adhesion proteins.
laminins, entacins, selectins, proteoglycans
Adhesion promoted by the _____ dependant Cadherins.
Ca2+
Gap Junctions
- types of “open” pores, and are more viable for intracellular transportation
- easily open for a chemical electrical gradient
- minerals go and pass between cells
Desmosomes
- form family of intracellular adhesion molecules with sides that have links to the membrane and an isoform from the other side of the cell
- linked together through the plaque and keratins (cytoskeletal fibers)
- Strong junctions found at base (hemidesmosome) and lateral portion of the cell
This network is primarily responsible for holding skin cells together and in makes up to 50% of the total protein of living skin cells,
Macula Adherens (Desmosomes)
Zonula Occludens
Tight Junctions
Stereocilia
- Non-motile surface area specializations that project into the lumen
- Protein core made of actin filaments with fimbrin cross-linking the filaments and ezrin attaching actin filaments to the membrane, alpha-actinin cross-links actin filaments at the base
- Very very long microvilli, 100x longer and are unable to bend, cilia do bend
Layers of epithelial cells.
Simple - single row of cells
Stratified - 2 rows of cells stacked together
Pseudostratified - ill-defined stack of cells
Cell shape.
Squamous - flattened
Cuboidal
Columnar
Transitional
Simple squamous epithelium
- single layer of flattened cells
Location: blood & lymphatic vessels (Endothelium); pericardium, peritoneum, (Mesothelium) - allows for a lot of fluid filtration
Simple cuboidal epithelium
Location: Ovaries, kidneys, certain glands (endocrine or exocrine), etc
Nonciliated simple columnar epithelium
Location: GI tract (excluding esophagus), certain ducts & gallbladder.
- Can be microvilliated or not
Ciliated simple columnar epithelium
Location: Respiratory tract, uterine tubes, PNS, spinal canal.
- trachea is the only place in the body that have cilia and microvilli together but this is not columnar epithelium, it is stratified squamous epithelium
Stratified squamous epithelium
Location:
Keratinized - Skin
Nonkeratinized- Wet surfaces: mouth, tongue, esophagus, vagina, etc
Stratified cuboidal epithelium
Location (more rare): Ducts of adult sweat glands, male urethra, ovum, etc.
Stratified columnar epithelium
Location: Part of the urethra, large glands (parotid), anal mucous membrane, part of conjunctiva.
- somewhat rare
Relaxed transitional epithelium (aka urothelium)
- combination of stratified cuboidal and stratified columnar, called “umbrella cells”
Location: Urinary bladder, part of the urethra & ureters
Pseudostratified columnar epithelium
Location:
Ciliated: Respiratory tract
Nonciliated: Large ducts of some glands, epididymis, part male urethra. bronchus and bronchi, nasal septum, and paranasal sinues.
- not stratified, it is actually simple columnar epithelium but the cells are arranged in a “checkerboard” fashion
- simple columnar is just arranged in single rows (this is what differentiates the two)
Glandular Epithelium-Endocrine
Location: Endocrine organs: pancreas, thyroid, pituitary, ovaries, testis, etc
PANCREAS: can do both exocrine and endocrine at the same time
- columnar epithelium and its arrangement is acinar
Glandular Epithelium - Exocrine
Location: Sweat, salivary, sebaceous glands
Two types of endocrine glands.
Follicle-like (thyroid) - secrete precursors of hormones into the follicular lumen and then is completed in the follicle
- has room to store so that is why it secretes precursors first
Cords-like (parathyroid) - release the hormone already in its final form
Exocrine glands.
Merocrine - salivary & pancreas, secrete little vesicles but cell structure is left intact
Apocrine - mammary glands, top of cell sheds off
Holocrine - skin sebaceous, whole cell sheds off
Ex- breast milk
